Ok. So, I should just Make-Stuff-Up, go from there, and have fun. I get it.
A lot of it kinda depends. There's a great series of books on the Soviet Air Forces in the Cold War, for example, but not so much detail online (that I've found anyways). If you're looking for something specific, I'm sure a lot of us would be able to help. Unfortunately, there's no one source or database to consult. Beyond time and country, the ease of finding info out is determined by branch of service and place of service too. For example wikipedia actually has great historical info for the USAF, but no so much the USN (especially if you're trying to find which specific carrier was where and with what air wing and aircraft - never mind escort ships). But there are other sources that have bits and pieces to help you build a bigger picture. Just takes some time, experience, and asking.